Transcortin

Transcortin, also known as corticosteroid-binding globulin (CBG) or serpin A6 is a protein that in humans is encoded by the SERPINA6 gene. It is an alpha-2 globulin that binds corticosteroids in the bloodstream and transports them to target tissues.

Function

Transcortin binds several steroid hormones at high rates, including cortisol, corticosterone, progesterone, and aldosterone. However, it has a particular affinity for cortisol, hence its alternative name, corticosteroid-binding globulin. The primary function of transcortin is to transport cortisol from the adrenal gland to target tissues and cells across the body.

Structure

Transcortin is a single-chain glycoprotein with a molecular weight of approximately 52,000. It is a member of the serpin family of proteins, which are known for their serine protease inhibitor activity, although transcortin does not exhibit this property.

Clinical significance

Abnormal levels of transcortin can lead to various health issues. Low levels can result in an excess of free cortisol, leading to Cushing's syndrome. Conversely, high levels can lead to a deficiency of free cortisol, potentially causing Addison's disease.

See also

• Cortisol
• Corticosteroid
• Serpin